Air conditioning system performance monitor

ABSTRACT

An air-conditioning system performance monitor measures the temperature of air on either side of the evaporator. Then a microcontroller means calculates the temperature drop in the air flowing across the evaporator. If the temperature drop is less than a predetermined threshold temperature, the microcontroller means alerts the house owner via display units, alarm, internet enabled devices and cell phones to call for service. This unit can be used on central air-conditioning systems, window air-conditioning systems and automobile air-conditioning systems.

PRIORITY CLAIM

This patent application claims priority from provisional U.S. patentapplication entitled “Air conditioning system performance monitor”having application No. 61/642,513 filed on May 4, 2012, the contents ofwhich are incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to monitoring the performance ofair-conditioning and refrigeration systems and alerting home owners orbuilding management to call for service when system performancedeteriorates.

BACKGROUND OF INVENTION

Air-conditioning systems work well when the refrigerant in the system isat the designed pressure, the air filter in the air-conditioning systemis not dirty and the blower motor is operating at the designed speed.Most often, the performance of the air-conditioning system deteriorateswhen the refrigerant pressure is lower than designed value or when theair filter is dirty. If the air-conditioning system is run for anextended period of time with improper refrigerant pressure, dirty airfilter or low blower motor speed, the air-conditioning system willconsume more energy but will not cool the living space sufficiently. Thecompressor will run hot and it will ruin the compressor. To avoid thesecostly problems, it is recommended to check the air-conditioning systemonce a year for optimal performance. Instead of annual check-up, if theperformance of the air-conditioning system can be monitoredcontinuously, then it is possible to detect any anomaly immediately andtake corrective action. This will prevent the compressor from gettingruined, save energy and save money. This invention sets out to do thisin a cost effective way.

SUMMARY OF INVENTION

The primary objective of the present invention is to monitor theperformance of air-conditioning systems continuously and alert the homeowner when the performance deteriorates. Here home owner is used to meanboth home owners in case of individual homes, drivers in case ofautomobiles and trucks and service personnel in case of apartmentcomplexes, office buildings, industrial installations etc.

Another objective of the present invention is to make it easy for anyoneto attach this invention to an existing air-conditioning system, whetherit is at home, office or in the automobile.

A third objective is to make this invention cost effective for theconsumers to buy and use.

The foregoing objectives are attained by having a programmablemicrocontroller monitor air temperature in the air-conditioning systemfor proper range and alert when the temperature difference falls outsidenormal temperature range.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangement of components set forth in the following description orillustrated in the drawings. The invention is capable of otherembodiments and of being practiced and carried out in various ways.Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of description and should not beregarded as limiting.

As such, those skilled in the art will appreciate that the concept, uponwhich this disclosure is based, may readily be utilized as a basis fordesigning of other structures, methods and systems for carrying out theseveral purposes of the present invention. It is important, therefore,that the claims be regarded as including such equivalent constructionsinsofar as they do not depart from the spirit and scope of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an evaluator means that measures airtemperature, evaluates performance of the air-conditioning system andcommunicates performance status to a notifier means.

FIG. 2 is a block diagram of said notifier means that communicates withone or more evaluator means of FIG. 1 and with other electroniccommunicating devices it is configured to communicate with such ascellular phones and internet enabled devices to disseminate theperformance information to the home owner.

FIG. 3 is a flowchart of the decision process used by a first embodimentof said evaluator means to determine if the air-conditioning system isoperating within its design parameters and to communicate with saidnotifier means about the status of the air-conditioning system.

FIG. 4 is a flowchart of the decision process used by the firstembodiment of said notifier means to determine when to alert the homeowner to call for service. The alert may be local using alarm means anddisplay means or through other electronic communication devices that areconfigured to communicate with said notifier means such as cell phonesand internet enabled devices.

FIG. 5 is a block diagram of evaluator means of the second embodimentfor automobile air-conditioning systems.

FIG. 6 is a flowchart of the decision process used by the secondembodiment of the invention to determine if the air-conditioning systemin the automobile is operating within its design parameters and tocommunicate the status to the driver of the automobile.

In this document, air-conditioning system means air-conditioner,air-conditioning system, refrigeration system and any system where airis drawn across an evaporator.

DETAILED DESCRIPTION OF THE INVENTION

The air-conditioning system is designed such that air flows across anevaporator and gets cooled. The design value for the air temperaturedrop across the evaporator in an air-conditioning system performing asper design specifications will be referred to henceforth as ideal-deltaTor IDT. With current technology, the value of IDT is about 17 degreesFahrenheit. When the refrigerant pressure is lower than the manufacturersuggested pressure, enough cooling of the evaporator does not take placeand the air temperature drop across the evaporator is less than IDT.Similarly, if the air filter is dirty, or the blower motor speed islower than designed value, enough air does not flow past the evaporatorto cool sufficiently. So by knowing the temperature drop across theevaporator of an air-conditioning system, we can determine theperformance of the air-conditioning system. Because of advances in theair-conditioning technology, this value of IDT can vary in future. Stillthis invention can be used once the proper value of IDT is used in theperformance evaluation process. A cutoff value, which is a few degreesFahrenheit lower than IDT may be allowed before the air-conditioningsystem is deemed to need servicing. This cutoff value in temperaturedifference, at which the air-conditioning system is deemed to needservicing will henceforth be referred to as threshold temperaturedifference or TTD.

The first embodiment of the invention consists of a plurality ofdetection and evaluation means, henceforth called evaluator1_cluster anda notifier means to notify the status of air-conditioning system,henceforth called notifier1. Each detection and evaluation means in saidevaluator) cluster will henceforth be referred to as evaluator1. Whenmultiple air-conditioning systems are involved as in office buildingsand large homes, each air-conditioning system will have one evaluator1.Hence said evaluator1_cluster will have a plurality of evaluator1. Whenthere is only one air-conditioning system involved, then saidevaluator1_cluster will have only one evaluator1. It would beadvantageous to have a single notifier1 collect the performance statusfrom each of a plurality of evaluator1 in said evaluator1_cluster andnotify the status of a plurality of air-conditioning systems in anaggregate manner. FIG. 1 is a block diagram of the electronic circuitinside said evaluator1. For central air-conditioning systems, evaluator1is mounted on the outside surface of plenum near the evaporator of theair-conditioning system. Referring to FIG. 1, evaluator1 consists of afirst electronic circuit board, 1, with a first microcontroller means 2.First microcontroller means, 2, is in electrical communication with afirst display means, 7, a first transceiver means, 8 and a plurality oftemperature sensor means which are divided into a plurality of inlet airtemperature sensor means, 3, and a plurality of outlet air temperaturesensor means, 4. First microcontroller means is also in electricalcommunication with a plurality of pressure sensor means, which aredivided into a first pressure sensor means, 5, and a second pressuresensor means, 6. FIG. 3 shows the decision logic used by said firstmicrocontroller means to determine the performance of theair-conditioning system.

Said plurality of inlet air temperature sensor means, 3, are placed inthe air flow just before the evaporator of the air-conditioning system.Said plurality of outlet air temperature sensor means, 4, are placed inthe air flow just after the evaporator. Said first pressure sensor meansis placed in the airflow just before the air filter in theair-conditioning system. Said second pressure sensor means is placed inthe airflow just after said air filter. Said first microcontrollermeans, 2, gets air temperature information from said plurality of inletair temperature sensor means and said plurality of outlet airtemperature sensor means. It calculates the average temperature dropacross the evaporator. If the calculated average temperature drop acrossthe evaporator is greater than or equal to TTD, it means theair-conditioning system is performing optimally. In this case, it checksthe status of the air-conditioning system stored in its memory duringone of the previous calculations. This status that is stored in memoryof said first microcontroller means will henceforth be calledmc1_status. If mc1_status is good, it means that the air-conditioningsystem status has not changed since previous calculation. So there is noneed to alert the home owner. In this case it checks said firsttransceiver means to see if it has received a status inquiry from saidnotifier1. If there is an inquiry, said first microcontroller meansfurnishes mc1_status to said notifier1 via said first transceiver means.In either case, whether there is a status inquiry or not, said firstmicrocontroller means waits for predetermined wait time and then repeatsthe process of getting temperature information from said plurality ofinlet air temperature sensor means and said plurality of outlet airtemperature sensor means. In FIG. 3, this is shown via33-34-35-36-38-47-48-49-33 process loop. If there is no status inquiryfrom said notifier1, then step 48 is not performed.

If, at decision point 38, mc1_status is other than good, it means thatthe status has now changed from other than good to good. It means thatthe problem experienced by the air conditioning system has beencorrected. In this case, said first microcontroller means updates mc1_togood. It then displays mc1_status via said first display means, 7. Saidfirst microcontroller means then checks said first transceiver means tosee if it has received a status inquiry from said notifier1. From thispoint on, the process is the same as for previously stated condition. InFIG. 3, this is shown via 33-34-36-38-39-46-47-48*49-33 process loop. Ifthere is no status inquiry from said notifier1, then step 48 is notperformed.

If the calculated average temperature drop across the evaporator is lessthan TTD, it means either the air-conditioning system is off or that itis not performing optimally. So said first microcontroller means checksto see if the calculated average temperature drop across the evaporatoris nearly equal to zero. If nearly equal to zero, it means that theair-conditioning system is presently turned off. In this case, saidfirst microcontroller means checks said first transceiver means to seeif it has received a status inquiry from said notifier1. From this pointon, the process is the same as for previously stated condition. In FIG.3, this is shown via 33-34-35-36-37-47-48-49-33 process loop. If thereis no status inquiry from said notifier1, then step 48 is not performed.

If the calculated average temperature drop across the evaporator is lessthan TTD but not nearly equal to zero, it means that theair-conditioning system is not performing optimally. In this case, saidfirst microcontroller means checks mc1_status. If this value representsother than good, it means that the non-optimal-performance of theair-conditioning system had already been determined in one of theprevious calculation cycles. In this case, said first microcontrollermeans checks said first transceiver means to see if it has received astatus inquiry from said notifier1. From this point on, the process isthe same as for previously stated conditions. In FIG. 3, this is shownvia 33-34-35-36-37-47-48-49-33 process loop. If there is no statusinquiry from said notifier1, then step 48 is not performed.

If, at decision point 40, said first microcontroller means finds thatmc1_status is good, it means that the air-conditioning system wasworking well till the previous calculation cycle. In this case, saidfirst microcontroller means obtains pressure readings from said firstpressure sensor means and said second pressure sensor means. If the twopressure readings are substantially the same, it means that the airfilter is not clogged. The problem could be the blower motor speed orthe refrigerant pressure in the system. Then it has to be serviced by aprofessional. In this case said first microcontroller means updatesmc1_status to indicate that a service call should be made. Afterupdating mc1_status, said first microcontroller means displaysmc1_status via said first display means, 7. Said first microcontrollermeans then checks said first transceiver means to see if it has receiveda status inquiry from said notifier1. From this point on, the process isthe same as for previously stated conditions. In FIG. 3, this is shownvia 33-34-35-36-37-40-41-44-46-47-48-49-33 process loop. If there is nostatus inquiry from said notifier1, then step 48 is not performed.

If, at decision point 42, the two pressure readings are not almost thesame, it means that the air filter is clogged and so there is asignificant pressure drop across the air filter. In this case said firstmicrocontroller means updates mc1_status to indicate that the air filtershould be changed. After updating mc1_status, said first microcontrollermeans displays mc1_status via said first display means, 7. From thispoint on, the process is the same as for previously stated conditions.In FIG. 3, this is shown via 33-34-35-36-37-41-42-43-46-47-48-49-33process loop. If there is no status inquiry from said notifier1, thenstep 48 is not performed.

FIG. 2 is a block diagram of the electronic circuit inside saidnotifier1. For homes, notifier1 is normally placed near the thermostatthat controls the air-conditioning system. For office buildings andindustrial establishments, it can be placed where other monitoringsystems are placed. Referring to FIG. 2, notifier1 consists of a secondelectronic circuit board, 11, with a second microcontroller means, 12.Second microcontroller means, 12, is in electrical communication with alight sensing means, 13, a second transceiver means, 14, a seconddisplay means, 15, an alarm means, 16 and a first user input means, 17.Said second transceiver means is configured to communicate seamlesslyand wirelessly with said first transceiver means of said evaluator1. Itis also configured to communicate seamlessly with user specified devicessuch as cellular phones and internet enabled devices. FIG. 4 shows thedecision logic used by said second microcontroller means to notify thestatus of air-conditioning system to the home owner.

Referring to FIG. 2 and FIG. 4, said second microcontroller means, 12,via said second transceiver means, 14, requests performance status fromeach said evaluator1 in said evaluator1 cluster. After a predeterminedwait time1, it checks to see if the performance status is received fromsaid evaluator1. If the performance status is received, it resets theretry count for that evaluator1 from which the performance status wasreceived. Then it checks the received status value against value in itsmemory for this evaluator1 which will henceforth be called mc2_status.If the two values are not the same, it means that the status has changedsince last check. It updates mc2_status with the received value anddisplays this new status on said second display means. It alsocommunicates, via said second transceiver means, updated status to userspecified devices such as cellular phones and internet enabled devicesthat are configured to communicate with said second transceiver means.Then it checks if the new status value corresponds to good performance.If it is not, said second microcontroller means checks to see if alarmcan be sounded anytime or it should be sounded only during daytime. Thisis because, if the air-conditioning systems monitored are in a locationwhere they should be working 24 hours a day and there is maintenancestaff working 24 hours a day, the alarm must be sounded when adversecondition is detected. If the monitored air-conditioning system is inthe house, sounding an alarm can wait till day time when people wouldhave woken up. If said second microcontroller means is configured toactivate alarm only during daytime, it checks input from said lightsensing means to determine if it is daytime before activating the alarm.If it is not daytime, said second microcontroller means waits tilldaytime to activate said alarm. Since it may take a few days to get theair-conditioning system serviced, the homeowner may acknowledge thealarm via said first user input means or any of the user specifieddevices such as cellular phones and internet enabled devices that areconfigured to communicate with said second transceiver means. Whilesounding the alarm, said second microcontroller means checks input fromsaid first user input means and said second transceiver means to see ifthere is a response from home owner acknowledging the alarm. If anacknowledgement is received, it deactivates the alarm, sets a wait flagto indicate to itself that after a few days or weeks, if the status hasnot changed, it should sound the alarm again. If there are moreevaluator1 in said evaluator1_cluster to be checked, said secondmicrocontroller means selects the next evaluator1 in evaluator1_clusterto send an inquiry via said second transceiver means. This portion ofthe logic is shown via63-64-65-66-72-73-74-75-76-77-81-82-84-85-86-87-88-89-69-70-64. If saidsecond microcontroller means is configured to activate said alarm evenduring night time, it bypasses checking whether it is daytime or not.This portion of the logic is shown via63-64-65-66-72-73-74-75-77-81-85-86-87-88-89-69-70-64.

If the home owner had serviced the air-conditioning system within thepredetermined servicing period, the performance status of theair-conditioning system would have been updated to good and so the alarmmeans would not be activated by said second microcontroller means, 12.If said second microcontroller means finds that mc2_status is good atdecision point 77, it resets the wait flag, and selects the nextevaluator1 in evaluator1_cluster to send an inquiry via said secondtransceiver means. From this point on, the process is the same as forpreviously stated conditions. This portion of the logic is shown via63-64-65-66-72-73-74-75-76-77-78-79-69-70-64.

If at decision point 73, said second microcontroller means finds thatthe received status value is the same as mc2_status, it checks if thewait flag is set. If set, it means that the air-conditioning systemstatus is not good. If the predetermined servicing period is over, saidsecond microcontroller means checks to see if it can activate said alarmat any time. From this point on, the processing is the same as mentionedbefore. This portion of the logic is shown via63-64-65-66-72-73-79-80-81-82-83-84-86-87-88-89-69-70-64 if alarm can beactivated only during daytime and via63-64-65-66-72-73-79-80-81-85-86-87-88-89-69-70-64 if alarm can beactivated at any time. If predetermined servicing period is not over, atdecision point 80, said second microcontroller means skips activatingalarm. This portion of the logic is shown via63-64-65-66-72-73-79-80-69-70-64. If the wait flag is not set atdecision point 79, it means that the air-conditioning system isperforming well and so said second microcontroller means selects thenext evaluator1 in evaluator1_cluster to send an inquiry via said secondtransceiver means. From this point on, the process is the same as forpreviously stated conditions. This portion of the logic is shown via63-64-65-72-73-79-69-70-64.

When said second microcontroller means sends an inquiry to saidevaluator1, it expects a response back from said evaluator1 within apredetermined wait time1. If a response is not received from saidevaluator1 within this time period, said second microcontroller meansincrements said retry count for this evaluator1. If the retry count isless than a predetermined number of tries, said second microcontrollermeans selects the next evaluator1 in evaluator1_cluster to send aninquiry via said second transceiver means. This portion of the logic isshown via 63-64-65-66-67-68-69-70-64. If the retry count exceedspredetermined number of tries, said second microcontroller means checksmc2_status. If mc2_status is other than check evaluator1, it means thatevaluator1 was responding till the last try. So said secondmicrocontroller means updates mc2_status to “check evaluator1”. Then itdisplays this updated status on said second display means. From thispoint on, the process is the same as for previously stated conditionwhen said second microcontroller means had to activate the alarm. Thisportion of the logic is shown via63-64-65-66-67-68-90-91-75-76-77-81-82-83-84-85-86-87-89-69-70-64 or via63-64-65-66-67-68-90-91-75-76-77-81-86-87-88-89-69-70-64. In the nextiteration, at decision point 90, mc2_status will reflect that theproblem with evaluator1 is a known problem. After a predeterminedservicing period, an alarm will be sounded as mentioned before. Thisportion of the logic is shown via 63-64-65-66-67-68-90-79-80.

When said second microcontroller means tries to select the nextevaluator1 in evaluator1_cluster, if it finds that said plurality ofevaluator1 has been exhausted, it waits a predetermined wait time2 andthen starts with the first evaluator1 in said evaluator1_cluster to sendan inquiry via said second transceiver means. This portion of the logicis shown via 69-70-71-63-64. Thus the embodiment presented is able tocontinuously monitor the health of the air-conditioning system and alertthe home owner to any problem with the air-conditioning system.

The second embodiment of the invention is for air-conditioning systemswhere said plurality of inlet air temperature sensor means and saidplurality of outlet air temperature sensor means cannot be placed oneither side of said evaporator easily. Some examples of such systems areair-conditioning systems in automobiles and window air-conditioners.Here the evaluator means, henceforth called car_evaluator1, is mountedin the vicinity of the vent through which cold air is blown. FIG. 5shows the block diagram for said car_evaluator1 and FIG. 6 shows thedecision logic used by said car_evaluator1. In FIG. 1, FIG. 3, FIG. 5and FIG. 6, like reference numerals designate like components anddecision process. Said plurality of outlet air temperature sensor meansis placed inside or very close to the vent blowing cold air and in thepath of cold air. Said plurality of inlet air temperature sensor meanswill be sampling the air temperature in the passenger area ofautomobiles and interior of room in window air-conditioners. and willnot be in the path of cold air blowing from the vent. For properreading, the air circulation system should be in recycle mode. In thiscase, the function of notifier means can also be integrated into saidcar_evaluator1 itself since the driver will be there when the alarm isactivated.

FIG. 5 is a block diagram of the electronic circuit inside saidcar_evaluator1. Referring to FIG. 5, car_evaluator1 consists of a firstelectronic circuit board, 1, with a first microcontroller means 2. Firstmicrocontroller means, 2, is in electrical communication with a firstdisplay means, 7, an alarm means, 21, a user input means, 20 and aplurality of temperature sensor means which are divided into a pluralityof inlet air temperature sensor means, 3, and a plurality of outlet airtemperature sensor means, 4. FIG. 6 shows the decision logic used bysaid first microcontroller means to determine the performance of theair-conditioning system.

Referring to FIG. 5 and FIG. 6, said first microcontroller means, 2,gets automobile cabin temperature information from said plurality ofinlet air temperature sensor means. It gets vent air temperature fromsaid plurality of outlet air temperature sensor means. It calculates theaverage temperature drop between said plurality of inlet air temperaturesensor means and said plurality of outlet air temperature sensor means.If the calculated average temperature drop is greater than or equal toTTD, it means the air-conditioning system is performing optimally. Inthis case, it checks mc1_status. If mc1_status is good, it means thatthe air-conditioning system status has not changed since previouscalculation. So there is no need to alert the driver of the automobile.Said first microcontroller means waits for predetermined wait time andthen repeats the process of getting temperature information from saidplurality of inlet air temperature sensor means and said plurality ofoutlet air temperature sensor means. In FIG. 6, this is shown via53-54-36-38-49-53 process loop.

If, at decision point 38, mc1_status is other than good, it means thatthe status has now changed from other than good to good. It means thatthe owner of the automobile has corrected the problem experienced by theair conditioning system. In this case, said first microcontroller meanschanges mc1_status to good and displays this new status via said firstdisplay means, 7. It then waits for predetermined wait time beforerepeating the process of getting temperature information from saidplurality of inlet air temperature sensor means and said plurality ofoutlet air temperature sensor means. In FIG. 6, this is shown via53-54-35-36-38-39-46-49-53 process loop.

If the calculated average temperature drop at decision point 36 is lessthan TTD, it means either the air-conditioning system is turned off orthat it is not performing optimally. So said first microcontroller meanschecks to see if the calculated average temperature drop is nearly equalto zero. If nearly equal to zero, it means that the air-conditioningsystem is presently turned off. In this case, it waits for predeterminedwait time before repeating the process. In FIG. 6, this is shown via53-54-35-36-37-49-53 process loop.

If the calculated average temperature drop at decision point 36 is lessthan TTD but not nearly equal to zero, it means that theair-conditioning system is not performing optimally. In this case, saidfirst microcontroller means checks mc1_status. If mc1_status is otherthan good, it means that the non-optimal-performance of theair-conditioning system had already been determined in one of theprevious calculations. In this case, it waits for predetermined waittime. From this point on, the process is the same as for previouslystated conditions. In FIG. 6, this is shown via 53-54-35-36-37-40-49-53process loop.

If, at decision point 40, said first microcontroller means finds thatmc1_status is good, it means that the air-conditioning system wasworking well till the previous calculation cycle. In this case, saidfirst microcontroller means updates mc1_status to indicate that aservice call should be made. After updating mc1_status, said firstmicrocontroller means displays mc1_status via said first display means,7. From this point on, the process is the same as for previously statedconditions. In FIG. 6, this is shown via 54-35-36-37-40-44-46-49-53process loop.

In the above discussion for both embodiments disclosed, said inlet airtemperature sensor means and said outlet air temperature sensor meanscan be thermistors, temperature sensing infrared detector means or anyother sensor means that provide an electrical output proportional to thetemperature read. Said first pressure sensor means and said secondpressure sensor means can be any device that can provide an electricaloutput proportional to the pressure read such as pressure transducers.Said first display means and said second display means can be an LCDdisplay, a set of LED lights or a single LED light blinking at differentrates to represent different mc1_statuses. Said light sensing means usedfor sensing ambient light level can be a photo transistor, a photodiode, a light dependent resistor, a ccd camera or any device that candetect light level in the surrounding area and provide an electricaloutput proportional to ambient light level. Said first user input meanscan be a keypad, a touch screen or just a switch.

Whenever the air-conditioning system is turned on or turned off, it willtake a few minutes for the system to reach stable operating condition.Hence said first microcontroller means will take multiple readings overa period of time to make sure the air-conditioning system has reachedstable operating condition. Temperature and pressure readings takenafter the air-conditioning system has reached this stable operatingcondition are used by said first microcontroller means to determine theperformance of the air-conditioning system.

What is claimed is:
 1. A performance monitoring system for monitoringperformance of air-conditioning systems comprising a notifier means anda plurality of evaluator means in an evaluator cluster; each saidevaluator means comprising: a) a first microcontroller means; b) aplurality of temperature sensor means in electrical communication withsaid first microcontroller means; c) a plurality of pressure sensormeans in electrical communication with said first microcontroller means;d) a first display means configured to receive display data from saidfirst microcontroller means and display received data; e) a firsttransceiver means in electrical communication with said firstmicrocontroller means to exchange a plurality of performance databetween said first microcontroller means and said notifier means; saidnotifier means comprising: a) a second microcontroller means; b) a lightsensing means in electrical communication with said secondmicrocontroller means; c) a second transceiver means in electricalcommunication with said second microcontroller means; d) an alarm meansin electrical communication with said second microcontroller means; e) asecond display means configured to receive display data from said secondmicrocontroller means and display received data; f) a first user inputmeans in communication with said second microcontroller means to provideuser communicated information to said second microcontroller means.
 2. Aperformance monitoring system of claim 1 wherein said plurality oftemperature sensor means are thermistors.
 3. A performance monitoringsystem of claim 1 wherein said plurality of temperature sensor means areinfrared detectors.
 4. A performance monitoring system of claim 1wherein said plurality of temperature sensor means comprise a pluralityof input air temperature sensor means and a plurality of output airtemperature sensor means.
 5. A performance monitoring system of claim 4wherein said plurality of input air temperature sensor means measure airtemperature before air passes through evaporator in saidair-conditioning system.
 6. A performance monitoring system of claim 4wherein said plurality of output air temperature sensor means measureair temperature after air passes through said evaporator in saidair-conditioning system.
 7. A performance monitoring system of claim 1wherein said plurality of pressure sensor means are pressuretransducers.
 8. A performance monitoring system of claim 1 wherein saidplurality of pressure sensor means consist of a first pressure sensormeans to measure air pressure immediately before air passes through anair filter in said air-conditioning system and a second pressure sensormeans to measure air pressure immediately after air passes through saidair filter.
 9. A performance monitoring system of claim 1 wherein saidfirst microcontroller means is configured to: a) accept temperaturereadings from said plurality of input air temperature sensor means andsaid plurality of output air temperature sensor means after eachpredetermined time interval and compute average temperature difference;b) accept pressure readings from said plurality of pressure sensor meansafter each predetermined time interval and compute pressure difference;c) determine operational state of said air-conditioning system to beoperating when said computed temperature difference is substantiallygreater than zero; d) determine operational state of saidair-conditioning system to be turned off when said computed temperaturedifference is substantially equal to zero; e) update previously storedstatus value to good when operational state is operating and saidcomputed temperature difference is not less than predetermined thresholdtemperature difference; f) update previously stored status value to airfilter change when operational state is operating and said computedtemperature difference is less than predetermined threshold temperaturedifference and calculated pressure difference is not substantially closeto zero; g) update previously stored status value to call service whenoperational state is operating and said computed temperature differenceis less than predetermined threshold temperature difference andcalculated pressure difference is substantially close to zero; h)communicate said updated previosly stored value to said notifier meansusing said first transceiver means when requested by said notifiermeans; i) communicate said updated previosly stored value to said firstdisplay means.
 10. A performance monitoring system of claim 1 whereinsaid first display means is a LCD display.
 11. A performance monitoringsystem of claim 1 wherein said first display means is a LED display. 12.A performance monitoring system of claim 1 wherein said firsttransceiver means is configured to communicate wirelessly with saidsecond transceiver means.
 13. A performance monitoring system of claim 1wherein said light sensing means communicates ambient light levelinformation to said second microcontroller means.
 14. A performancemonitoring system of claim 13 wherein said light sensing means is aphoto diode.
 15. A performance monitoring system of claim 13 whereinsaid light sensing means is a charge coupled device.
 16. A performancemonitoring system of claim 13 wherein said light sensing means is alight dependent resistor.
 17. A performance monitoring system of claim 1wherein said alarm means produces audible sound.
 18. A performancemonitoring system of claim 1 wherein said second transceiver means isconfigured to communicate wirelessly with a plurality of said firsttransceiver means of said plurality of evaluator means and a pluralityof user specified cellular phones and internet enabled devices.
 19. Aperformance monitoring system of claim 1 wherein said secondmicrocontroller means is configured to: a) communicate with each saidevaluator means in said evaluator cluster using said second transceivermeans; b) retry predetermined number of times over a predetermined timeinterval to communicate with each said evaluator means before alertinguser of problem with said evaluator means; c) update previously storedstatus value with received status value when received status valuedifferent from previously stored status value; d) communicate saidreceived status value to said second display means when said receivedvalue different from said previously stored status value; e) communicatesaid received status value to said plurality of user specified cellularphones and internet enabled devices when said received value differentfrom said previously stored status value; f) activate said alarm meansat any time when said received status value is other than good; g)activate said alarm means when said light sensing means indicatesdaytime and said received status value other than good and said secondmicrocontroller means configured to activate alarm means only duringdaytime; h) deactivate said alarm means when so directed; i) updatepreviously stored status value to check said evaluator means when noresponse received from said evaluator means over multiple tries overmultiple predetermined time intervals.
 20. A performance monitoringsystem of claim 1 wherein said second display means is a LCD display.21. A performance monitoring system of claim 1 wherein said first userinput means is a keyboard.
 22. A performance monitoring system of claim1 wherein said first user input means is a switch.
 23. A performancemonitoring system of claim 1 wherein said first user input means is atouch screen.
 24. A method for monitoring performance ofair-conditioning systems comprising a notifier means communicating witha plurality of evaluator means in an evaluator cluster; each saidevaluator means computing temperature drop across evaporator ofair-conditioning system comprising the steps: a) providing a pluralityof input air temperature sensor means capable of measuring airtemperature before air passes through said evaporator in saidair-conditioning system; b) providing a plurality of output airtemperature sensor means capable of measuring air temperature after airpasses through said evaporator in said air-conditioning system; c)providing a first pressure sensor means capable of measuring airpressure just before air reaches air filter in said air-conditioningsystem; d) providing a second pressure sensor means capable of measuringair pressure just after air passes said air filter in saidair-conditioning system; e) providing a first microcontroller meanscapable of determining the performance of said air-conditioning system;f) providing a first display means capable of receiving performancestatus data from said first microcontroller means and displaying tousers; g) providing a first transceiver means capable of communicating aplurality of performance data between said first microcontroller meansand said notifier means. Said notifier means performing the steps of: h)collecting a plurality of performance data from a plurality of evaluatormeans in said evaluator cluster; i) notifying performance status of eachair-conditioning system to user.
 25. The method of claim 24 wherein instep e) the first microcontroller means determines the performance ofsaid air-conditioning system by: a. accepting temperature reading fromsaid plurality of input air temperature sensor means and said pluralityof output air temperature sensor means after each predetermined timeinterval; b. computing average temperature difference between saidplurality of input air temperature sensor means and said plurality ofoutput air temperature sensor means; c. accepting pressure readings fromsaid first pressure sensor means and said second pressure sensor meansafter each predetermined time interval; d. computing pressure differencebetween said first pressure sensor means and said second pressure sensormeans e. determining operational state of said air-conditioning systemto be operating when said computed temperature difference issubstantially greater than zero; f. determining operational state ofsaid air-conditioning system to be turned off when said computedtemperature difference is substantially equal to zero; g. updatingpreviously stored status value to good when operational state isoperating and computed temperature difference is not less thanpredetermined threshold temperature difference; h. updating previouslystored status value to air filter change when operational state isoperating and computed temperature difference is less than predeterminedthreshold temperature difference and calculated pressure difference isnot substantially close to zero; i. updating previously stored statusvalue to call service when operational state is operating and computedtemperature difference is less than predetermined threshold temperaturedifference and calculated pressure difference is substantially close tozero; j. communicating said updated previosly stored value to saidnotifier means using said first transceiver means when requested by saidnotifier means; k. communicating said updated previosly stored value tosaid first display means.
 26. The method of claim 24 wherein in step h)the notifier means collects a plurality of performance data from aplurality of evaluator means in said evaluator cluster by: a)communicating after every predetermined time interval, with each saidevaluator means in said evaluator cluster using said second transceivermeans; b) retrying predetermined number of times over a predeterminedtime interval to communicate with each said evaluator means beforealerting user of problem with said evaluator means; c) updatingpreviously stored status value with received status value when receivedstatus value different from previously stored status value; d)communicating said received status value to said second display meanswhen said received value different from said previously stored statusvalue; e) communicating said received status value to plurality of userspecified cellular phones and internet enabled devices; f) activatingsaid alarm means any time when said received status other than good; g)activating said alarm means when said light sensing means indicatesdaytime and said received status other than good and said secondmicrocontroller means configured to activate alarm means only duringdaytime; h) deactivating said alarm means when so directed by user. i)updating previously stored status value to check said evaluator meanswhen no response received from said evaluator means over multiple triesover multiple predetermined time intervals.
 27. A performance monitoringsystem for monitoring performance of air-conditioning systemscomprising: a) a first microcontroller means; b) a plurality oftemperature sensor means in electrical communication with said firstmicrocontroller means; c) a first display means configured to receivedisplay data from said first microcontroller means and display receiveddata. d) an alarm means in electrical communication with said firstmicrocontroller means; e) a user input means in communication with saidfirst microcontroller means to provide user communicated information tosaid first microcontroller means.
 28. A performance monitoring system ofclaim 27 wherein said plurality of temperature sensor means arethermistors.
 29. A performance monitoring system of claim 27 whereinsaid plurality of temperature sensor means are infrared detectors.
 30. Aperformance monitoring system of claim 27 wherein said plurality oftemperature sensor means comprise a plurality of input air temperaturesensor means and a plurality of output air temperature sensor means. 31.A performance monitoring system of claim 30 wherein said plurality ofinput air temperature sensor means measure air temperature in automobilecabin.
 32. A performance monitoring system of claim 30 wherein saidplurality of output air temperature sensor means measure air temperaturesubstantially close to automobile cabin vent.
 33. A performancemonitoring system of claim 27 wherein said first microcontroller meansis configured to: a) accept temperature readings from said plurality ofinput air temperature sensor means and said plurality of output airtemperature sensor means after each predetermined time interval andcompute average temperature difference; b) determine operational stateof said air-conditioning system to be operating when said computedtemperature difference is substantially greater than zero; c) determineoperational state of said air-conditioning system to be turned off whensaid computed temperature difference is substantially equal to zero; d)update previously stored status value to good when operational state isoperating and said computed temperature difference is not less thanpredetermined threshold temperature difference; e) update previouslystored status value to call service when operational state is operatingand said computed temperature difference is less than predeterminedthreshold temperature difference; f) communicate said updated previoslystored value to said first display means; g) activate said alarm meanswhen said updated previously stored status value is other than good; h)deactivate said alarm means when so directed using user input means. 34.A performance monitoring system of claim 27 wherein said first displaymeans is a LCD display.
 35. A performance monitoring system of claim 27wherein said first display means is a LED display.
 36. A performancemonitoring system of claim 27 wherein said alarm means produces audiblesound.
 37. A performance monitoring system of claim 27 wherein said userinput means is a keyboard.
 38. A performance monitoring system of claim27 wherein said first user input means is a switch.